The invention relates to a
cathode material, alpha-Fe2O3, of a high-capacity
lithium ion battery and a preparation method for the
cathode material. According to the preparation method, soluble trivalent molysite and an
alkali metal hydroxide easy to dissolve are adopted as raw materials, and the
hematite alpha-Fe2O3 is prepared by a hydrothermal method. The preparation method comprises the following specific steps that: 1)
aqueous solution of the trivalent molysite with molarity being 0.5mol / L-2mol / L and
aqueous solution of the
alkali metal hydroxide easy to dissolve with molarity being 2mol / L-6mol / L are prepared; 2) the
aqueous solution of the trivalent molysite and the aqueous solution of the
alkali metal hydroxide obtained in the step 1) are mixed to generate suspension, the suspension is stirred for certain time, and then
ammonia water drops into the suspension, so that the pH value of the suspension is adjusted to be 9-13; and 3) the suspension obtained in the step 2) is poured into a
hydrothermal reaction kettle which can be airtight, the
hydrothermal reaction kettle is put into an oven to be heated at a temperature of 160 DEG C-200 DEG C and then is subjected to
thermal insulation for 3 hours to 20 hours, and after the reaction is finished, a product is subjected to
solid-liquid separation, washing and
drying so as to obtain the alpha-Fe2O3. When serving as the
cathode material of the
lithium ion battery, the alpha-Fe2O3 prepared by the method has higher specific capacity and better
cycling stability. According to the method, the operation is simple, the cost is low, additives are not required, and the product quality is stable.